基于LPV模型的风能转换系统增益调度控制

在额定风速以下,风能转换系统需要通过控制发电机转速使风能的捕获率最大.根据风速的多时间尺度特性,建立风能转换系统的非线性机理模型,进一步得到其归一化误差的线性参数变化(LPV)系统模型;为获取最大风能捕获和减少机械振荡,在PI控制策略的基础上,利用基于LPV模型的增益调度控制器进行动态补偿.仿真结果表明:补偿后系统的功率系数和叶尖速比追踪其最优值的精度更高,鲁棒性更好,体现了更好的动态性能.     

风能转换系统的LPV主动容错控制

随着对风力机效率和可靠性要求的提高,现代风力机不再如传统风力机那样一味追求高的产能。本文针对桨距执行器故障的风能转换系统具有非线性性和参数严重不确定性,提出了基于LPV增益调度的风能转换系统的主动容错控制方法,降低故障对机组动态特性的影响。基于LPV凸分解方法,将风能转化系统非线性模型化为具有凸多面体结构LPV模型,利用LMI技术对凸多面体各个顶点分别设计满足性能要求的控制器,再利用各顶点设计的反馈控制器得到具有凸多面体结构LPV容错控制器。仿真结果表明,LPV增益调度技术可以成功地应用于风能转换系统的容错控制,在有故障的情况下,仍能保持系统的稳定和良好的动态性能。     

中立时滞LPV系统基于观测器的控制器设计

研究一类中立时滞线性参数变化系统的基于观测器的控制问题．呆用Lyapunov方法,提出了系统的时滞相关稳定性条件,设计了增益调度控制器和状态观测器．利用参数线性矩阵不等式,将控制器存在的充分条件转化为凸优化问题．最后通过数值仿真验证了所提出方法的可行性．     

风能转换系统执行器故障重构与容错控制

针对风能转换系统中执行器故障,论文提出了一种新型的主动容错控制策略.设计滑模故障观测器,实时动态采集执行器故障前后数据信息,对执行器故障进行重构,达到故障诊断的目的.通过补偿控制,保证了滑模控制器对风能转换系统的可靠控制输入,以达到对执行器故障主动容错的功能.仿真结果表明,滑模故障观测器模块能够实时精确地重构风能转换系统执行器故障,主动补偿容错控制器在不影响风能转换系统动态性能的情况下,仍能实现系统的最大风能的捕获.     

风能转换系统执行器故障主动容错控制

提出了一种新颖的风能转换系统滑模主动容错控制策略.针对风能转换系统执行器故障,运用预测控制思想和迭代算法,设计了一种故障观测器.在设定的优化时域长度内,利用实际系统与故障观测器的输出差值,通过反复迭代运算,不断地对虚拟故障信号进行调整,使其能有效地拟合实际系统执行器故障,并根据故障观测值实时调整滑模容错控制器结构.未发生故障时,故障观测值为零,系统在滑模控制器控制下稳定运行;执行器发生故障时,运用故障观测值实时调整滑模容错控制项,并用双曲正切函数代替符号函数,消除抖动.仿真实验结果表明,滑模容错控制器下的系统具有良好的容错能力,提高了风能转换系统最大风能捕获效率.     

具有时变时延的网络化LPV系统的容错控制

针对一类具有时变时延以及Lipschitz非线性项的网络化线性参数变化系统,研究了系统中存在外部扰动、执行器和传感器同时发生随机故障时的容错控制问题。用Bernoulli分布序列描述执行器和传感器发生的随机故障,利用自由权矩阵方法处理时变时延。根据Lyapunov-Krasovskii稳定性定理和线性矩阵不等式（LMI）方法求出◢H◣▼∞▽容错控制器存在的充分条件,然后通过利用近似基函数和网格化技术将无限维的LMI求解问题转换为有限维的LMI问题,得到了相应的容错控制器增益。最后,通过数值仿真验证了所设计方法的有效性。     

永磁同步发电机风能转换系统滑模控制仿真

针对由于风速的随机波动性而使基于线性定常控制器的风能转换系统稳定性较差的问题,提出了一种基于滑模控制的永磁同步发电机风能转换系统的设计方案;分析了该系统中风力机模型、传动装置模型和永磁同步发电机模型的建立原理,介绍了滑模控制策略的具体实现。仿真结果表明,该系统具有较好的速度跟踪特性,实现了最大风能捕获。     

非线性系统近似最优PD动态补偿控制

本文研究了一类基于动态补偿的非线性系统的近似最优PD控制的问题.用微分方程的逐次逼近理论将非线性系统的最优控制问题转化为求解线性非齐次两点边值序列问题,并提供了从时域最优状态反馈到频域最优PD控制器参数的优化方法,从而获取系统最优的动态补偿网络,设计出最优PD整定参数,给出其实现算法.最后仿真示例将所提出的方法与传统的线性二次型调节器（LQR）逐次逼近方法相比较,表明该方法具有良好的动态性能和鲁棒性.     

线性参数变化系统建模与控制研究进展

在描述实际系统的非线性和时变特性方面, 线性参数变化(Linear parameter varying, LPV)模型有着巨大的优越性, 对于使用一些成熟的线性系统控制理论来解决非线性系统的控制问题, 提供了良好的手段.文章对LPV系统的模型结构和建模方法, 模型参数辨识方法, 控制方法以及应用领域等方面的近几年的研究成果, 做了比较全面的总结和概括, 最后对LPV系统建模和控制的未来研究方向进行了展望.     

两自由度机械手逆系统动态补偿解耦控制

本文对综合非线系统的一种新方法－逆系统解耦控制进行了研究，并以自行设计的两自由度机械手为对象，实现了仿真及实时控制。     

基于线性模型跟随的风力发电功率解耦控制

本文首先对包括风力机、无刷双馈发电机的风力发电系统进行建模, 并通过同步坐标变换分解为两个解耦子系统. 在此基础上, 采用双环控制使系统跟随参考模型的特性. 由功率特性曲线可知, 某一风速对应特定的最大功率. 针对无刷双馈发电机的复杂结构, 在控制系统的内环采用自抗扰控制, 可以很好的实现功率解耦控制; 外环采用线性模型跟随控制, 使得发电机能够很好的跟随模型特性. 仿真结果表明, 双环控制器可以使系统的输出功率快速的跟踪给定的功率, 实现完全模型跟踪, 证明了控制算法的有效性.     

Energy-based coordinated control of wind energy conversion system with DFIG

This article presents an energy-based coordinated control of machine- and grid-side converters in a wind energy conversion system (WECS) with a doubly-fed induction generator (DFIG) based on the theory of port-controlled Hamiltonian (PCH) system. Taking into account energy transmission in the dual PWM converter rather than treating rectification and inversion as separate parts, an integrated PCH model for the whole WECS was established from physical meanings. And depending on the new model, an energy-based coordinated control approach was proposed to meet the control requirements of the WECS with an additional objective which was to limit the DC-link voltage fluctuation. The approach was applied on a 2MW WECS, and compared with the energy-based respective control strategy using MATLAB/Simulink. The results show that the proposed control approach provides faster dynamic performance since the two converters operate with the knowledge of each other's operating status, and thus is able to smooth the power flow in the DC-link more effectively.     

额定风速以上风力发电机组的恒功率H∞鲁棒控制

风力发电机组由于机械结构以及电气负荷承受能力的限制存在着转速限制和功率限制, 额定风速以上时,需要通过控制桨距角来实现额定恒功率输出, 同时保持转速在额定转速处. 本文建立了风力发电机组的详细机理模型, 将H_∞控制理论应用到额定风速以上时风力发电机组的恒功率输出的控制器设计, 建立了标准H_∞恒功率控制问题. 利用LMI方法求解, 得到了桨距角的H_∞控制器. 仿真结果表明该H_∞控制器能够成功实现额定风速以上时的恒功率输出控制, 并且具有良好的鲁棒性.     

Output feedback control of wind energy conversion system involving a doubly fed induction generator

This paper deals with the problem of controlling a wind energy conversion system (WECS) based on the doubly fed induction generator (DFIG), by IGBT‐based back‐to‐back rectifier‐inverter. The goal of control is to maximize wind energy extraction letting the wind turbine rotor operate in a variable‐speed mode. Interestingly, the present study features the achievement of the above energetic goal without resorting to sensors for wind velocity. The control strategy involves: (i) an output feedback non‐linear regulator designed by the backstepping technique and based on the use of a high gain observer; (ii) a sensorless online reference‐speed optimizer designed using the turbine power characteristic to achieve the maximum power point tracking (MPPT) requirement. It is formally shown that the proposed controller actually meets its control objectives. This theoretical result is confirmed by several simulations.     

Output feedback robust MPC for LPV system with polytopic model parametric uncertainty and bounded disturbance

The output feedback robust model predictive control (MPC), for the linear parameter varying (LPV) system with norm-bounded disturbance, is addressed, where the model parametric matrices are only known to be bounded within a polytope. The previous techniques of norm-bounding technique, quadratic boundedness (QB), dynamic output feedback, and ellipsoid (true-state bound; TSB) refreshment formula for guaranteeing recursive feasibility, are fused into the newly proposed approaches. In the notion of QB, the full Lyapunov matrix is applied for the first time in this context. The single-step dynamic output feedback robust MPC, where the infinite-horizon control moves are parameterised as a dynamic output feedback law, is the main topic of this paper, while the multi-step method is also suggested. In order to strictly guarantee the physical constraints, the outer bound of the true state replaces the true state itself, so tightness of this bound has a major effect on the control performance. In order to tighten the TSB, a procedure for refreshing the real-time ellipsoid based on that of the last sampling instant is given. This paper is conclusive for the past results and far-reaching for the future researches. Two benchmark examples are given to show the effectiveness of the novel results.     

An observer‐based output feedback robust MPC approach for constrained LPV systems with bounded disturbance and noise

The present paper addresses an observer‐based output feedback robust model predictive control for the linear parameter varying system with bounded disturbance and noise subject to input and state constraints. The main contribution is that the on‐line convex optimization problem not only simultaneously optimizes the observer and controller gains to stabilize the augmented closed‐loop system but also incorporates the refreshment of bounds of the estimation error set. The optimization problem steers the nominal augmented closed‐loop system to converge to the origin, and the real augmented closed‐loop system bounded within robust positive invariant set converges to a neighborhood of the origin such that recursive feasibility of the optimization and robust stability of the controlled system are ensured. Two numerical examples are given to illustrate the effectiveness of the method.     

LPV decoupling for control of multivariable systems

This article investigates methods for decoupling multivariable linear parameter varying (LPV) systems and proposes a new interaction measure for decoupled proportional-integral (PI) feedback control design in LPV systems. The proposed approach seeks to benefit the multivariable control of multi-input multi-output (MIMO) systems with variable operating conditions, variable parameters or nonlinear behaviour. This method can improve the tracking performance and reduce the operating conditions variability of such systems with significant coupling in the system dynamics. We design MIMO decoupling feedback LPV controllers to address loop interaction effects. The proposed method uses a parameter-dependent static inversion or SVD decomposition of the system to minimise the effects of the off-diagonal terms in the MIMO system transfer function matrix. A new parameter-dependent interaction measure is introduced based on the SVD decomposition and static inversion which is subsequently utilised for tuning multi-loop PI controller gains. Numerical examples are presented to illustrate the validity of the proposed LPV decoupling methods, as well as the use of the proposed interaction measures for a decoupled multi-loop PI control design.